5 Jun
2008
5 Jun
'08
5:35 p.m.
On Wed, 2008-06-04 at 11:46 +0200, Stefano D'Angelo wrote:
For example, I'm not sure whether not having that
feature prevents or
makes it hard somehow to do stuff like DJ-style scratching or speed
changing effects with sample-level accuracy.
To do a scratching effect, you actually need a resampler and then play
the resampled data back at the original samplerate. When scratching,
both the pitch and the speed of the sound goes up and down depending on
the speed of the disc.
To do that with digital audio you must either change the sample rate of
the data or the interface. Because you can't continuously change the
sample rate of a pc sound interface, you must resample the data.
The pitch or and speed matching stuff dj's do is exactly the same. They
can just match either one (unless they're really lucky) because both
change when the one parameter (the speed of the disc).
Rubberband ( http://breakfastquay.com/rubberband/ ) contains a plugin
(ladspa) that can change only the pitch of an audio stream.
All of these effects have a strict 1:1 ratio between samples going in
and going out. The only effect which differs in this would be changing
the 'length' of the signal, but that is a different story altogether.
I hope I got your original question right. If I didn't, sorry for the
noise everyone :)
Sampo